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Subject[PATCH v2 02/17] KVM: async_pf: Add helper function to check completion queue
Date
This adds inline function kvm_check_async_pf_completion_queue()
and stub on !CONFIG_KVM_ASYNC_PF so that the source code won't
have to care about CONFIG_KVM_ASYNC_PF. The kernel option is
used for once in kvm_main.c and it can be removed then. Besides,
the checks on the completion queue are all replaced by the newly
introduced helper as list_empty() and list_empty_careful() are
interchangeable.

The stub kvm_check_async_pf_completion() on !CONFIG_KVM_ASYNC_PF
is also introduced. It will be used by subsequent patch.

Signed-off-by: Gavin Shan <gshan@redhat.com>
---
arch/x86/kvm/x86.c | 2 +-
include/linux/kvm_host.h | 12 ++++++++++++
virt/kvm/async_pf.c | 12 ++++++------
virt/kvm/kvm_main.c | 4 +---
4 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 76bce832cade..f3c9fe5c424e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10794,7 +10794,7 @@ static inline bool kvm_guest_apic_has_interrupt(struct kvm_vcpu *vcpu)

static inline bool kvm_vcpu_has_events(struct kvm_vcpu *vcpu)
{
- if (!list_empty_careful(&vcpu->async_pf.done))
+ if (kvm_check_async_pf_completion_queue(vcpu))
return true;

if (kvm_apic_has_events(vcpu))
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index b6697ee1182e..041d93f8f4b0 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -316,11 +316,23 @@ struct kvm_async_pf {
bool notpresent_injected;
};

+static inline bool kvm_check_async_pf_completion_queue(struct kvm_vcpu *vcpu)
+{
+ return !list_empty_careful(&vcpu->async_pf.done);
+}
+
void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu);
void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu);
bool kvm_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
unsigned long hva, struct kvm_arch_async_pf *arch);
int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu);
+#else
+static inline bool kvm_check_async_pf_completion_queue(struct kvm_vcpu *vcpu)
+{
+ return false;
+}
+
+static inline void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu) { }
#endif


diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c
index dd777688d14a..2cf864aafd0e 100644
--- a/virt/kvm/async_pf.c
+++ b/virt/kvm/async_pf.c
@@ -70,7 +70,7 @@ static void async_pf_execute(struct work_struct *work)
kvm_arch_async_page_present(vcpu, apf);

spin_lock(&vcpu->async_pf.lock);
- first = list_empty(&vcpu->async_pf.done);
+ first = !kvm_check_async_pf_completion_queue(vcpu);
list_add_tail(&apf->link, &vcpu->async_pf.done);
apf->vcpu = NULL;
spin_unlock(&vcpu->async_pf.lock);
@@ -122,7 +122,7 @@ void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu)
spin_lock(&vcpu->async_pf.lock);
}

- while (!list_empty(&vcpu->async_pf.done)) {
+ while (kvm_check_async_pf_completion_queue(vcpu)) {
struct kvm_async_pf *work =
list_first_entry(&vcpu->async_pf.done,
typeof(*work), link);
@@ -138,8 +138,8 @@ void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu)
{
struct kvm_async_pf *work;

- while (!list_empty_careful(&vcpu->async_pf.done) &&
- kvm_arch_can_dequeue_async_page_present(vcpu)) {
+ while (kvm_check_async_pf_completion_queue(vcpu) &&
+ kvm_arch_can_dequeue_async_page_present(vcpu)) {
spin_lock(&vcpu->async_pf.lock);
work = list_first_entry(&vcpu->async_pf.done, typeof(*work),
link);
@@ -205,7 +205,7 @@ int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu)
struct kvm_async_pf *work;
bool first;

- if (!list_empty_careful(&vcpu->async_pf.done))
+ if (kvm_check_async_pf_completion_queue(vcpu))
return 0;

work = kmem_cache_zalloc(async_pf_cache, GFP_ATOMIC);
@@ -216,7 +216,7 @@ int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu)
INIT_LIST_HEAD(&work->queue); /* for list_del to work */

spin_lock(&vcpu->async_pf.lock);
- first = list_empty(&vcpu->async_pf.done);
+ first = !kvm_check_async_pf_completion_queue(vcpu);
list_add_tail(&work->link, &vcpu->async_pf.done);
spin_unlock(&vcpu->async_pf.lock);

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 8367d88ce39b..632b80b6e485 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2961,10 +2961,8 @@ static bool vcpu_dy_runnable(struct kvm_vcpu *vcpu)
if (kvm_arch_dy_runnable(vcpu))
return true;

-#ifdef CONFIG_KVM_ASYNC_PF
- if (!list_empty_careful(&vcpu->async_pf.done))
+ if (kvm_check_async_pf_completion_queue(vcpu))
return true;
-#endif

return false;
}
--
2.23.0
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